Wind turbines create power proportional to the swept area of their blades. Wind turbines having longer blades will increase the swept area, which in turn produces more power. At high wind speeds, a wind turbine having longer blades places greater demands on the components and creates more situations where the turbine must be shut down to avoid damaging components. Even in situations where the average wind speed is not high enough to cause damage, periodic wind gusts apply forces that may be strong enough to damage equipment. Accordingly, choosing a rotor diameter for a wind turbine has conventionally been a design trade-off between longer blades for more energy production in low winds and shorter blades for load limitation in high winds.
Variable length rotor blade systems have also been used in an attempt to achieve higher power, and experience fewer shut downs and less damage to components. In such systems, the wind turbine rotor blades are telescopic so that their length can be adjusted based on the wind speed. The rotor blades can be extended to provide higher output in low wind conditions and retracted to lower loads in high wind conditions. U.S. Pat. No. 6,902,370 discloses a wind turbine system having telescoping wind turbine rotor blades.